The limiting aeration condition necessary to produce the collapse of established pipes is evaluated in a flat bottomed aerated silo. The main parameters tested are the powders properties and the width of the aeration pad at the silo bottom. The measured quantities are the aeration rates and the corresponding size of the pipe. The gas pressure gradient close to the pipe is estimated from the numerical solution of the air flow field in the bulk solids in the hypothesis of Darcy flow regime. The powder permeability necessary for this calculation is estimated by fluidization experiments. The hoop stress evaluated according to Johanson is in good agreement with the unconfined yield strength of the powder provided that the contribution of aeration to powder consolidation during pipe formation is properly accounted for.
A study on the effect of air humidity on powder flow properties
LANDI, GIOVANNA;BARLETTA, Diego;DONSI', Giorgio;FERRARI, Giovanna;POLETTO, Massimo
2008-01-01
Abstract
The limiting aeration condition necessary to produce the collapse of established pipes is evaluated in a flat bottomed aerated silo. The main parameters tested are the powders properties and the width of the aeration pad at the silo bottom. The measured quantities are the aeration rates and the corresponding size of the pipe. The gas pressure gradient close to the pipe is estimated from the numerical solution of the air flow field in the bulk solids in the hypothesis of Darcy flow regime. The powder permeability necessary for this calculation is estimated by fluidization experiments. The hoop stress evaluated according to Johanson is in good agreement with the unconfined yield strength of the powder provided that the contribution of aeration to powder consolidation during pipe formation is properly accounted for.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
